What's the best way to find the cemetary / city my grandfather was buried in?

?? the legal standard for location of burial (or disposition of body ie cremation) is legally required on the death certificate. SOME DEATH CERTS are online but those are the exception, not the rule.

Seems that you have not purchased or found that record. Findagrave.com is a fantastic site.. but you seem to overlook, it is a volunteer site, with no guarantee of every burial in the country.

Your mistake seems to be that you expect all genealogy to be online, which is not the case.

Since you didn't include details (ie name/date/location), I am limited to being able to help. I know which Texas certs are online, I know where Arizona certs are online. Both are limited to specific time frames.

You are welcome to repost your question with details and someone may be able to find this. Otherwise, if you want to do IN DEPTH successful research, you need to broaden your perspective.

You could look for his obituary in the newspaper, which may name the place of burial. Depending on when and where he died, you might be able to find it online. If not, the local library may have the newspaper on microfilm. You'd have to either go there to look at it, or ask the librarian if they will do a lookup for you.

If that doesn't work, you could order a copy of his death certificate from the Department of Health or Vital Records Office in the state where he died. The death certificate should list the place of interment.

Or you could post his name and death date/location here and see if anyone can help locate the info. Some of the regulars here are brilliant at tracking down this type of info.

If you are American my understanding is that US death certs show place of burial, so apply for a copy of his death certificate.

If not then you have an idea of what city/town he was buried in, the do a search for the cemeteries that are in that location then contact the cemetery office which hold details of all burials ( and cremations).....

Local library will have newspapers you can search for an obituary ( if one was written) which sometimes tells you where the service and burial is going to be

The internet is only a reference book it isn't a magic box of tricks and if someone doesn't upload this information into eg findagrave hen of course it won't be there, same as the commercial sites, if they have collected the information from people who pay to use and store all there added information they wouldn't have all the collected data information for others to find